Gnip, a social media data company, created an interactive map that displays all geo-tagged tweets since September 2011, down to the city level. The data collected includes over 2.7 billion data points. Gnip says the breakdown of Android and iPhone owners correlates to wealthier and poorer parts of each city.

Here’s s a look at a few major U.S. cities. iPhone users are represented by red; Android users are represented by green.